N-heterocyclic carbene catalyzed alpha-redox reaction has been utilized towards the catalytic synthesis of amides utilizing amines and substoichiometric quantities of an acyl transfer reagent in a waste reduced acylation process. The reaction is amenable to a plethora of amines and amine hydrochloride salts as nucleophiles. The reaction is applicable towards a variety alpha-reducible aldehydes as alpha,alpha-dichloro aldehydes, enals, epoxy and aziridnyl aldehydes all provide the respective amides in moderate to excellent yields with the latter in high diastereoselectivity. The asymmetric amidation reaction provides chiral amides in moderate enantioselectivity.
Additionally, the N-heterocyclic carbene catalyzed alpha-redox reaction was also utilized for the synthesis of enantioenriched alpha-chloro and alpha-fluoro carboxylic acids. The reaction also provide for a mild installation of a deuterium from D2O furnishing enantioenriched isotopically labeled compounds. Investigations in to the mechanism have revealed that the carbene displays behavior of a phase transfer reagent by shuttling hydroxide from the aqueous phase to the organic phase. Additionally, it has been found that the turover limiting step in this acylation process in the hydrolysis of the acyl azolium.
|Commitee:||Chen, Eugene, McNeil, Michael, Williams, Robert M., Wood, John L.|
|School:||Colorado State University|
|School Location:||United States -- Colorado|
|Source:||DAI-B 73/04, Dissertation Abstracts International|
|Keywords:||Acylation, Alpha-redox reactions, Amidation, Asymmetric, Catalysis, N-heterocyclic carbene catalysis, Synthesis|
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